﻿using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace CommonHelper
{
    /// <summary>
    /// 加密解密帮助类；
    /// </summary>
    public static class EncryptionHelper
    {
        /// <summary>
        /// 偏移量
        /// </summary>
        private static byte[] iv = { 102, 16, 93, 156, 78, 4, 218, 33 };//定义偏移量

        /// <summary>
        /// 密钥
        /// </summary>
        private static byte[] key = { 55, 103, 246, 79, 36, 99, 167, 5 };//定义密钥

        #region MD5加密

        /// <summary>
        /// MD5加密
        /// </summary>
        /// <param name="strSource">需要加密的字符串</param>
        /// <returns>MD5加密后的字符串</returns>
        public static string Md5Encrypt(string strSource)
        {
            //把字符串放到byte数组中
            byte[] bytIn = System.Text.Encoding.Default.GetBytes(strSource);
            //实例DES加密类
            DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();
            mobjCryptoService.Key = iv;
            mobjCryptoService.IV = key;
            ICryptoTransform encrypto = mobjCryptoService.CreateEncryptor();
            //实例MemoryStream流加密密文件
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Write);
            cs.Write(bytIn, 0, bytIn.Length);
            cs.FlushFinalBlock();

            string strOut = System.Convert.ToBase64String(ms.ToArray());
            return strOut;
        }

        #endregion MD5加密

        #region MD5解密

        /// <summary>
        /// MD5解密
        /// </summary>
        /// <param name="Source">需要解密的字符串</param>
        /// <returns>MD5解密后的字符串</returns>
        public static string Md5Decrypt(string Source)
        {
            try
            {
                //将解密字符串转换成字节数组
                byte[] bytIn = System.Convert.FromBase64String(Source);
                DESCryptoServiceProvider mobjCryptoService = new DESCryptoServiceProvider();
                mobjCryptoService.Key = iv;
                mobjCryptoService.IV = key;
                //实例流进行解密
                System.IO.MemoryStream ms = new System.IO.MemoryStream(bytIn, 0, bytIn.Length);
                ICryptoTransform encrypto = mobjCryptoService.CreateDecryptor();
                CryptoStream cs = new CryptoStream(ms, encrypto, CryptoStreamMode.Read);
                StreamReader strd = new StreamReader(cs, Encoding.Default);
                return strd.ReadToEnd();
            }
            catch
            {
                return "";
            }
        }

        #endregion MD5解密
    }
}
